1. Technical Field
The present disclosure relates to a charging-control apparatus and a charging-control method.
2. Background Art
In vehicles such as a car, an alternator (generator) is rotated by an output of an engine to generate electric power. The generated electric power charges a secondary battery and drives various loads (e.g., an electric steering).
Charging control which is performed when charging a secondary battery with an alternator is realized by controlling a power generation voltage of the alternator by a regulator in such a manner that a voltage of the secondary battery comes to a preset voltage. In a common charging control apparatus, in order to perform the charging of the secondary battery efficiently, the preset voltage is set to be higher than a rated voltage (e.g., 12V). I.e., the preset voltage is set to be around 13.5-14.5V. However, with such a control, in a state where the vehicle is running at a high speed and an electric load is low, it comes to an over-charged state which causes an increase in the burden on the engine, a decrease in fuel consumption rate, and an increase in a lowering of a fluid level of the secondary battery.
Thus, according to the technique described in Japanese Laid-Open Patent Publication No. S62-37025, a voltage of a secondary battery is detected, and when the voltage drops to a value below a predetermined value, it is determined to be in an over-discharged state and the preset voltage is raised to increase a charge acceptance capability, and when the detected voltage of the secondary battery is higher than the predetermined value, it is determined to be in an over-charged state and the preset voltage is lowered to suppress the charge acceptance capability.
A voltage of the secondary battery may be, for example, due to influences of polarization and stratification, outputted as a voltage higher than a voltage corresponding to an actual charging rate. Accordingly, since the voltage is high even though the charging is actually insufficient, when the preset voltage is set to be low, and there is a possibility that the capacity becomes insufficient. Also, while the vehicle is running at a high-speed, even if the voltage of the secondary battery is kept high on average, there is a possibility that the capacity becomes insufficient depending on the state of the load.
Thus, it is an object of the present disclosure to provide a charging control apparatus and a charging control method that are capable of efficiently performing charging control of a secondary battery.